The overall objective of the research is to continue investigations related to modification of radiation response. Currently our main interests are in the area of hyperthermia by itself and its interaction with x-irradiation. We also are examining the possible use of ultrasound as a treatment modality, both for the induction of hyperthermia and as a cytotoxic agent. In vitro studies are aimed primarily at determining how hyperthermia inactivates cells, particularly effects on plasma membranes. Tumor studies in mice are designed to evaluate the role of combined hyperthermia and x-irradiation in eradicating a variety of murine tumors. Temperature studies, optimum sequence, and methods of thermal delivery are investigated.